<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <!--选择器-->
    <style>
        /* *{
            color:  red;
            font-size: 30px;
        } */

        span{
            color: red;
        }

        h3{
            color:green;
        }
    </style>
</head>
<body>
    <p>hello world</p>
    <h3>hello html</h3>
    <ul>
        <li>列表1</li>
        <li>列表2</li>
    </ul>

    <p>我是<span>网页</span></p>
</body>
</html>